Summer-winter control instrument



juiy Q, 1946. G. l. HOLMES 2,

SUMMER-WINTER CONTROL INSTRUMENT I Filed May- 4, 1942 2 Sheets-Sheet 10LJNG1 EA-1N6, MEANS MEANS H u 25' INVENTOR.

Gifioka. I; Holmcbs BY jam Afforney Patented July 9, 1946 SUMMER-WINTERCONTROL INSTRUMENT Giflord I. Holmes, 'Minneapolis, Minn, assignor toMinneapolis-Honeywell Regulator Company, Minneapolis, Minn., acorporation of Delaware Application May 4, 1942, Serial No. 441,648

. 1 Thisapplication is a continuation in part of my copendingapplication Serial No. 301,900 filed October 30, 1939, as to all mattercommon to the two applications. The subject matter of these relatedapplications and common-to both, involves improvements in thermostaticdevices. Application Serial No. Patent No. 2,309,193, dated Jan. 26,1943.

The present invention relates to summerwinter control instruments andmore particularly to such instruments and the circuitstherefor embodyingnovel means for obtaining automatic change over from heating to coolingand vice versa. g V

In heating and cooling control it is conventional practice to make useof a plurality of controlling instruments together withrnanual means forchanging control from one to the other thereof at different seasons ofthe year. Such systems therefore comprise some duplication of parts. Afurther disadvantage of present systems resides in this need for manualchange-over. In the spring and fall of the year in some sections of thecountry, both heating and cooling may be needed in the same day, or fromday to day. Hence, the householder must operate the changeover means agreat number of times inorder to obtain the desired operation of theheating and cooling means.

In the prior art it has become more and more common to supply bothheating and cooling in buildings and in dwellings. In these heating andcooling systems it has become a conventional practice to equip thesystems with a plurality of controls. These controllers take the form ofthermostats. The first of the controllers may control the cooling systemand the second controller would control the heating system. In the eventthat it is desired to change from heating to cooling, it is necessary togive manual attention to the system to either place one or the other ofthe controllers into control. Because of the complicated nature of someof these systems it has been found necessary to give skilled attentionto the control systems. For this reason the systems have not met withready approval under many circumstances.

An example of the undesirability of heating and cooling systems needingmanual changeover is in the domestic air conditioning field.

Here the controller is placed within the dwelling space in the buildingand the occupants thereof usually adjust the control means from time totime to the desired setting. If two controls Were employed for a manualchange-over switch, it is 301,900 has become 13 Claims. (01. 257 3conceivable that the occupants of the dwelling might adjust the heatingmeans below the cooling means with the result that both would be.

in operation simultaneously.

Another feature. that has been found highly desirable in heating andcooling systems is that feature known as delayed heating. or coolinganticipation. This type of function in a system, consider heating forexample, .is' that after the thermostat has called for-heat and a slightrisel in temperature occursin the space, the operation of the thermostatwill be' accelerated to thereby open the control contacts to terminateoperation of the burner. Such operation will anticipate the delivery ofheat to the space prior to the actual delivery thereof. With such asystem overshooting in the space is prevented. Upon operatingon.thecooling cycle it is 'de-. sirable when the space, begins to coolto speedup oraccelerate the operation ofthe' thermostat to cause .thecooling means to be deenergized and thus anticipate the cooling inthespace to thereby prevent over-shooting.

Another desirable feature in a thermostat of v the naturesetoutaboveis'in automatic changeover from heating to cooling, and vice versa;With. this automatic change-over during the spring and fall of the year,when heating and cooling may be needed from day to day or at differenttimes during the same day, the cooling devices will automaticallyenergize either the cooling or the heating means as indicated by'thetemperature afiecting the bimetallic element.

It is, therefore, an object of the present invention to providea'heating and cooling system hav ing automatic change-over controlmeans.

A further object of the present invention is to provide an automaticchange-over control means utilizing snap action switch means forenergizing either the cooling or the heating means.

Another object 'of'the present invention is to provide .an automaticchange-over switch with heating anticipation when the device isoperating on the heating cycle and cooling anticipation when thedeviceis operating on the cooling cycle.

A further object is to provide a novel type of cooling anticipation to asystem forcontrolling a cooling means.

Another object is to provide an automatic change-overI-switch withheating means whereby the device will have a very small change-overtemperature differential.

The aboveand other objects will be apparent in the accompanyingspecification and claims. I

In the drawings,

Figure 1, is a diagrammatical view of one embodiment of my invention.

Figure 2 is a diagrammatical view of a modification thereof.

And Figure 3 is a diagrammatical view similar to Figure 1, but of amodification thereof.

Referring first to Figure 1, a heating means I8 and a cooling means IIare controlled by relays I2 and I3, respectively. The heating relay I2comprises a winding I4 which when energized through circuits to behereinafter traced pulls in relay arms I5, I6 and I1. These relay armscooperate with stationary contacts I8, I9 and 28, respectively. Suitablebiasing means are provided for return of the said relay arms to theposition shown in Figure 1 upon the deenergization of the winding I4.The contacts I6 and I9 are in control of the heating means I8 and acircuit therefor may be traced as follows: from the line wire 25 throughconductor 26, relay arm I6, contact I9, conductor 21, the heating meansI8 and the conductor 28 back to the other line wire 29. It is seentherefore that when the relay winding I4 is energized a circuit forplacing the heating means in operation is closed.

The relay I3 comprises a winding 38 which when energized moves movablecontacts 3|, 32, 33, 34, and 35 toward the left. These contactscooperate with stationary contacts 38, 31, 38, 39, 48, and 4|,respectively. Suitable biasing means are provided for return of the saidrelay arms or movable contacts to the position shown in Figure 1 uponthe deenergization of the winding I4. The movable contact arm 35 and thestationary contact 4| control the operation of the cooling means II.When contact 4| is engaged by the arm 35 a circuit for the cooling meansII may be traced as follows: from the line wire 25 through conductor 45,relay arm 35, contact 4|, conductor 46, cooling means II, and conductor41 back to the other line wire 29. From tracing the foregoing circuit itis seen that when the relay winding 38 is energized that a circuit forthe cooling means is completed so that the cooling means II will beplaced into operation. Energy for actuating the relays I2 and I3 issupplied from a transformer generally indicated by the referencecharacter 58. The transformer 58-comprises a primary winding and a lowvoltage secondary winding 52. Also in control of these relays is acontrol device generally indicated by the reference character 55.

The control device 55 comprises a base 56 having a pivot post 51 securedthereto. Upon the post 51 a bimetallic member 58 is freely mounted by abracket 59. The bimetallic member 58 is arranged so that upon atemperature decrease the ends of the bimetal member 58 will tend to moveapart and upon an increase in temperature these ends will move closer toeach other. Upon the lower right-hand end of the bimetallic strip 58 arecarried a plurality of movable heating control contacts 68 and 6|,respectively. The contact 6| is mounted upon a resilient strip 52 sothat the contact 6| may be pushed back to permit engagement of thecontact 68 with its stationary contact for a purpose to be hereinaftermore fully pointed out. The contact 6| cooperates with a stationarycontact 63 which is mounted upon a conducting bracket 64 which mayextend out from the rear of the base 56. The movable contact 68cooperates with a stationary contact 65 which is carried upon aconducting bracket 66 which likewise may extend upwar ly fr m the rearof the base 56.

At the lower left-hand end of the bimetal strip 58 are a pair of movablecooling control contacts 18 and 1|. The contact 1| is mounted at thelower end of a resilient strip 12 so that contact 1I may be pushed backwhen engaging its stationary contact to permit engagement of contact 18with its stationary contact. The contact 1| cooperates with a stationarycontact 13 carried upon a bracket 14 which is in turn mounted to amovable insulating panel 15. The movable contact 18 cooperates with astationary contact 16 which is secured to a bracket 11 also carried bythe panel 15.

A pair of adjustable abuttable contacts 88 and BI are suitably mountedon posts 82 and 83, respectively, which are secured to the movableinsulating member 15. The contacts 88 and 8| may be bridged by aconducting plate 85 which is mounted by means of insulation 86 upon thelower left-hand end of the bimetal strip 58. The contacts 88 and 8| whenbridged are adapted to complete circuits used in connection with theheating contacts mounted on the lower righthand end of the strip 58.These contacts may also be adjusted to vary the relative spacing of theheating and cooling contacts, to thus vary the changeover temperaturedifierential. The purpose of these various contacts will be more fullydescribed hereinafter.

A pair of abuttable cooling control contacts 98 and 9| are suitablymounted upon posts 92 and 9-3, respectively. The contacts 98 and 9| areadapted to be bridged by a conducting plate 94 which is mounted upon aninsulating piece 95 carried by the lower right-hand end of the thermalstrip 58. The contacts 98 and 3| when bridged are adapted to cooperatewith circuits controlled by the cooling contacts carried by the lowerleft-hand end of thebimetal strip 58. The operation of this portion ofthe controller will be hereinafter more fully described.

The insulating panel 15 is adapted to be moved either to the right or tothe left by its mounting arm I88 which is pivoted on the post 51. Thepurpose of moving the arm I88 to thereby move the insulating panelcarrying the stationary contacts as well as the abuttable contacts is sothat an adjustment-for the device may be obtained. The upper endof armI88 is bifurcated to form a pair of fingers I8I and I82. The finger I82is biased to the left by a spring I83 which at its other end is securedto an upturned ear I94 on the base 56. The spring I83 normally biasesthe finger I8| into engagement with a day adjustment cam I85. The camI85 is non-rotatably fixed upon a post 386 which in turn may be rotatedby an adjustment dial I81 carrying temperature indicia I88. The indiciaI88 cooperates with a pointer I89 to indicate the position of the dayadjustment cam I85. As the adjustment dial 8? is rotated, the cam I85will be rotated to a similar degree to thereby vary the position of thefinger I8| and hence the position of the arm I88. When the adjustmentdial I81 is moved in a counter-clockwise direction the finger IIJI willmove to the left. Movement to the left of the finger I8I will cause thearm I88 to be moved toward the right. With such adjustment it is seenthat the bimetal strip 58 will have to heat up before it will actuateany of the contacts carried by its lower left-hand end. Hence, it isseen that an adjustment to increase the control setting of the device isobtained. Moving the dial I81 in the opposite direction converselylowers the control point.

A night adjustment cam H is suitably secured to a night adjustment dialI I I carrying indicia similar. to the dial; I01. The finger I02cooperates with thecam III! to determine the position to which thethermostatic strip 58 is moved for shut-down operation during certain.portions of the day, usually at night time. I

A spring operated time motor for shifting the device over from daytonight operation is generally indicated by the reference character II5. The: timing motor comprises a suitable spring operated clockwork,not. shown, which rotates a cam member I IS. The cam is adapted to movea cam follower II! to one, of two positions. The cam follower, II! isshown in a drop-off portion 1 i8. which is the normal position for thefollower during the day time. When the cam III; is rotated to the rightby turning a winding knob I I9, the camfollower II I will ride up asurface I29 whereupon a drop-01f piece IZI which is biased into theposition shownin the drawings will be pushed back until the cam followerI I1 passes the riser portion I20.

Thetime motor I 15 is designed so that it may be set by turning a manualknob I25 at the time of setting so that the hour of the day registerswith a Window in they case indicated in broken lines at IZE. After thisadjustment is made, the winding. knob H9 is rotated in a clockwisedirection so that the cam follower II! will drop into the drop-offportion H8 at a second, predetermined time. For. example, it might beassumed that it is twelveoclock in the evening at the position of theparts shown in the drawings. Now

, assume it is desired for the morning pickup period for the thermostat58to begin at six oclock in the morning. The winding knob H9 wouldmerely be turned around until the numeral 6 carried on a dial I21appeared in the window I26.

With such adjustment of the clock mechanism H it would take six hoursbefore the cam follower II'I would drop into the lower detent portionH8.

The cam follower II I carriesa resilient arm I30. When the spring armI3!) is in the position shown it is adapted to permit the spring I 03connected to the adjustment finger I02 to move the adjustment finger IoIinto engagement with a day adjustment cam I35. Hence, when the camfollower II! is in the position shown, the thermostat 53 will controlunder the day setting determined by the adjustment of the cam IIl'I.

When the arm I33 is: in the position shown, a pair of contacts I31 andI32 are bridged by a portion thereof. It will be understood that thecontacts could be bridged by some suitable pressed back contactstructure carried upon the arm I30 if desired. When the contacts I3! andI32 are bridged the circuit for the cooling cycle is placed in conditionfor control by the thermostat as'will be hereinafter more fullydescribed. When the cam follower Ill rides up onto the high surface ofthe cam II 6, the spring arm I30 is moved toward the left. Movement ofthe arm I30 toward the left will move the insulating panel I5 toward theleft. The amount of movement of the panel will be determined now by theadjustment of the night setting cam III When the arm I90 is rotated:toward the left the adjustment ringe I!!2 thereof will move into.engagement with the adjustment cam III]. The spring arm. $3.0 isstrongenough to overcome the spring I23. connected to the arm I92 so theadjustment finger I02. will move into engagement with the cam. I II).which will determine the night 6. adjustment-icithe thermostat'55. Uponmoving the spring arm [30 to. the left in the. manner above described,the contacts I3! and I32 will be unbridgecl. The purpose of this actionis to prevent operation of the cooling means when shutting down: thetemperature at'night. A sec"- ond' purpose for unbriclging the contactsI3I and i32 is to: give. night shut downwhen the device is operating on.its. cooling cycle so that the coolin: means maybe placed out ofoperationduring a; desired portion of the day.

Agsrnall spring I,3.5 is connected to the righthand leg of the bimetalstrip 53Iand to the ad-' -lusting: arm IIIBIL. The spring I35 exertssufficient.

force upon the bimetal strip-58v so as to tend to turn the same on thepivot 51in a: clockwise direction causing the abutting contacts 80, BI.or the contacts 20 and GI to be engagedwith suflicient: pressure togive. good: electrical contact; However; the spring I351 does noteXertsufiicient force to substantially vary the operation of the bimetallicstrip 58. A heater Mil is arranged so as to ant-feet the: bimetallicstrip 58 by means of local heating under certain circumstances. Inactual construction of the device the heater Mil might take the form ofa plug mounted upon the pivot .51 to affect equally'bcth sides of thebimetal 58. However for purposes of illustration, the heater I49: isshown diagrammatically as" being arranged adjacent only the right-handside of the bimetalstrip 58-.

Heating operation towards the left so that. this action will take placefirst Thereafter, upon further cooling. of the thermostatic strip. 5athe lower rightehand end thereot willmovetoward the right. The movablecontact 6i will first engage its stationary contact. 63. 'At. this. timehowever,.,no circuit is completed for the relay winding I4 becausev themovable contact arm I5 of the relay I2 will be out of engagement withits stationary contact I8 and there will be no circuit to the relay coilI4. Upon further cooling of the thermostatic strip 58;. the contact 6!]will engage the stationary contact 65. At this time, a circuit for therelay winding IA of the relay l2 may be traced from thetransformersecondary 52 as follows: from wire I45 through wire I45,contact bracket 64, stationary contact as, movable contact 6|, flexiblestrip 52, contact iii], stationary contact 65, conducting bracket wireI41, relay winding I I. wire I43 and wire I49 back to the other side ofthe transformer secondary 52. Energization of the relay winding I4causes the movable contacts I5,- If' and I-I' to be moved towards theright and results in engagement of the contacts I8 and I9 by theirrespective movable contact arms I5 and I6. Engagement of contacts IE andI9 will cause energization of the heating means through the circuitpreviously traced.

Operation of th heating means It will result in an increaseintemperature in the space in which the thermostat 55 is located. Afterthe temperatureeof the space rises. slightly the movable. contact. 6%.will. move out of engagement with its stationary contact 65 but thecontact 6| will remain in engagement with its contact 63 because of .thepressback due to its mounting On the resilient blade 62.

At the time contacts 60 and I55 separate, a holding circuit for therelay winding I4 of the relay I2 may be traced as follows: from thetransformer secondary 52 through wires I45, I45, bracket 64, contacts 63and BI, flexible blade 62, bimetal strip 53, mounting bracket 59, wireI50, wire II, abuttable contact BI, bridge 85, contact 80, wire I52,heater I45, wire I53, contact I8, contact blade I5, wire I54, relaywinding I4,

.wire I48 and wire I49 back to the other side of the transformersecondary 52. It will be noted that this circuit includes the heater I40adjacent the bimetal strip 58. Although this circuit including thisheater is closed immediately when the relay I2 pulls in, the resistanceI40 will be shunted out by the contacts 60 and 55 so that this heaterwill not be brought into operation until after contacts 60 and 65 areopened.

The heater I40 may be so selected so as to give substantially threedegrees of heat to the bimetallic strip 58. Hence, after the contacts 60and 65 open and the circuit previously traced including the heater is incontrol of the relay l2 a certain amount of heat will be given off tothe bimetal. This will result in a speed up in operation of thebimetallic strip 58 in a heating direction which will tend to op t e otacts and 63 to deenergize the heating relay I2. Deenergization of theheating relay I2 will result in shutting off of the heating means. Fromthe foregoing it is seen that I have provided a delayed heatanticipation action on the heating cycle.

For night shut down while operating on the heating side of the system,the clock mechanism II5 is adjusted at some desired time at night topick up again at a predetermined time in the morning. To adjust thedevice, the knob I I9 is rotated in a clockwise direction to move thecam follower II! and the spring blade I30 connected thereto toward theleft. This will result in shifting the insulating panel I5 carried uponthe adjustment arm I I30 toward the left. It will also result in openingthe contacts I3I and I32 to the cooling system so that the cooling meanswill not I be started during this time. Moving of the panel toward theleft will make it necessary for the thermostatic strip 58 to expand moreor in other words to cool further before closing contacts GIL-65 tostart the heating operation. Hence, it is seen that the thermostaticstrip 58 will now control at a low temperature which is determined bythe adjustment of the night shut-down cam III. Otherwise, the operationof the heating relay I2 is identical to that discussed hereinbefore. Inother words, the last to make contacts 60 and 65 must close before therelay winding I4 is energized and the last to open contacts BI and 63which are in circuit with the heater I40 control the holding circuit tothe relay I2. Therefore, it is seen that the present device givesdelayed heat anticipation on both day and night operation.

When the winding I4 of the heating relay I2 is energized, the movablecontact I'I moves out of engagement with an out contact 20. The reasonfor this is to prevent a holding circuit from being set up for the heatcontrol relay winding I4 which would be independent of the movableheating thermostatic contacts 50 and 6 I.

Changeover operation If the thermostatic strip 58 is heated upindicating that the ambient temperature is rising due to externalconditions, for example the outdoor temperature, the lower right-handend of the bimetallic strip 58 will move toward the left. After movingthrough a predetermined range of movement, for example 3 temperaturechange after the contact 6| moves out of engagement with the stationarycontact 63, the bridge piece 94 will engage the abuttable contacts SI]and 9|. At this time a circuit for the heater I40 may be traced asfollows: from the transformer secondary 52 through wire I45, wire I58,relay arm I1, out contact 20 of relay I2 which is deenergized at thistime, wire I6I, a variable resistance I62, wire I63, out contact 40 ofthe cooling means control relay It, contact arm 34, wire I64, heater Miwire N55, abuttable contact 9|, bridge piece 54, contact 99, and wireI65 back to the other side of the transformer secondary 52. On tracingthe above circuit, it is seen that the heater 549 is energized and aspreviously discussed, is adapted to supply substantially 23 of heat tothe bimetal strip 58, Additional heat being applied to the strip 58 willresult in the movable contacts ill and II carried at the lower left handend thereof moving into engagement with their respective stationarycontacts. By such operation, it is seen that I have provided a switchchangeover device which is substantially capable of controlling eitherheating or cooling at approximately the same temperature.

On changeover in the opposite direction heat is removed from the bimetal58 when the bridge plate 94 separates from contacts 90 and GI to therebyspeed up cooling action of the bimetal.

Cooling operation When the movable contact II carried upon the flexiblecontact mounting strip 12 at the lower left hand end of the bimetallicstrip 58 moves into engagement with its stationary contact it, nocircuit will be established for the relay It because the holdingcontacts 36 and BI of the relay l3 will not at this time be inengagement. However, when the movable contact 76 engages the stationarycontact l5 an energizing circuit for the relay winding of the relay i3may be traced as follows: from transformer secondary 52 through wireI45, wire IIll, contact I32, spring I39, contact I3I, wire I'll,conducting bracket I I, contact 13, contact II, resilient arm 72,contact 1E3, stationary contact I6, conducting bracket 11, wire I12,relay winding 30, wire H3, relay arm 33, out contact 38, wire I14, andwire 149 back to the other side of the transformer secondary 52. Theabove traced circuit will cause pulling in of the relay I3 andengagement of the relay ,arm with its stationary contact 4| as well asall of the other left-hand stationary contacts of the relay. Engagementof contacts 35 and II will result in energization of the cooling meansII through the circuit hereinbefore traced for said means.

It will be noted that the heater I40 is energized upon the bridging ofthe contacts 80 and 9| by the plate 94 prior to the energization of thecooling means I I. Moreover it will be seen that when relay coil 30 isenergized and the cooling means thereby placed in operation the heaterI48 remains energized through a new circuit as follows: from thetransformer secondary 52 through wires I and III], contact I32, springI30, contact I3I, wire I'II, contact bracket i4, contacts 9 Hand II,contact carrying blade I2, contacts I and I6, contact bracket 11, wireI12, relay winding 30, wire I13, relay arm 32, contact 31, wire I15,contact 39, relay arm 34, wire I64, heater I40, wire I65, contact 9|,bridge piece 94, contact 90, and wire I66 back to the other side of thetransformer secondary 52, The original relay circuit was broken at 3338and the previously traced original circuit for heater I40 was broken .at34-40 upon initial energization of relay coil 30. I

.From tracing the foregoing circuits it will be seen that the variableresistance I62 which was in series with the heater Mt when the relay I3was deenergized is now not in the circuit. The variable resistance I52is so selected that its impedance will be approximately the same aseither of the relay windings or I4. The reason for this is so that theresistance I will give approximately the same heating, for example 3",whether the relay winding I4 is in series therewith or the relay winding38, or the variable resistance I52. By this structure it is seen that anexact temperature can be supplied tothe bimetal underdifferentconditions and under diiferent controlling operations in heating andcooling. With the cooling means in operation, bimetal element 53 willcool and first open contacts l0-l"6.

When the contact 70 leaves its stationary contact 16 it is desirable tohave less heat generated by the heater I40 aifect the bimetallic strip50 to accelerate cooling of the strip. For this reason, I have devised acircuit which places a larger resistance in the holding circuit afterthe contact in separates from the stationary contact it. This circuitmay be traced as follows: from transformer secondary 52 through wires Iand I10, contact 5.3.2, spring 530, contact I3I, wire Ili, contactbracket 1 3, contacts 13 and I I, contact blade 12, bimetallic strip-58, thermostat mounting bracket =59, wire 15c, wire I80, a relativelylarge resistance ISI, wire I82, holding contact36, relay arm 3!, wireI83, relay winding 30, wire I13, relay arm 32, contact 3?, wire I'ifi,contact .39, relay arm 34, wire I64, heater I40, wire I05, contact 9|,bridge E i, contact 90, and wire I156 back to the other side of thetransformersecondary'52. It will be noted that in the above circuit thelarge resistance element I8I is in series with the heater i' iri. Theresistance I8I .may be so selected that the current flow through theabove traced circuits wiil be just sufiicient to keep the relay winding.35 energized. Hence, the potential drop through the big resistance WIand the relay winding 30 will be so large that very little heat willemanate from the heater I40. This will remove most of the 3 of heattheretofore furnished the bimetal E8, causing it to cool, This coolingwill result in the ends of the bimetal moving in cooling direction toaccelerate the opening action between the contacts H and 73. Hence, thisaction might be termed delayed cooling anticipation. Separation ofcontacts H and "I3 will of course result in breaking the holding'circuitpreviously traced to deenergize the relay and to cause the cooling meansto be deenergized.

It will be noted upon referring again to the energizing circuit for-thecooling relay I3 that the coil '30 i energized throughan out contact 38engaged by an out contact arm 33. It will also be noted that theenergized position of the relay depends upon the engagement of relaycontact 31 with relay arm 32 and relay contact '39 with arm 34. It isnecessary to have certain overlapping in the operation of these relaycontact arms. As illustrated in the drawings, the relay arm 34 may beflexible and engage the stationary contact 39 prior to opening of thecontact 38. Likewise, the contact 38 is adapted to remain closed untilthe stationary contact 31 is engaged by the arm 32. Thus it is seen thatsufficient overlap is provided so that the relay will be positivelyenergized and remain energized until separation of the holding contactsII and '73.

It has been found in practicing the conditioning art that it issometimes desirable to modify the operation of the system down at night.My novel device not only provides for lowering the temperature at nighton the heating cycle in the manner hereinbefore described, but alsodeenergizes the cooling means at night so as to completely shutoff thecoolingoperation during the night. To accomplish this, it is simplynecessary for an operator to rotate the adjustmentarm I I9 to thedesired setting, which operation will cause separate breaking of thecircuit {through the contacts I3I and I32 which in normal day operationare bridged by the spring member I30. The cam follower III is shown inFigure 1 in the position which it normally takes for day operation forthe device. Hence, in setting the clock mechanism I I5 in the abovedescribed manner the circuit to the cooling relay I3 will be broken fora time predetermined by the setting of the clockwork mechanism .5. wayaffect the heating contact inasm ch as they will be moved still furtheraway from the stationary contacts 63' and 65. Hence it is seen that Ihave provided a device for automatic changeover from .heating to coolingcontrol wherein the changeover degree of differential is kept at aminimum and wherein night shut-down may be provided whethe operatingupon the heating or cooling cycleof the system.

The modification shown in Fig. 2

Referring now to Figure 2, a heating means 200 and a cooling means 20Iare controlled ,respectively by a heating relay 202 and a cooling relay203. The heating relay 202 comprises ;a relay .winding 202a which whenenergized moves a pair of movable contactblades 206 and 20'! ,intoengagement with stationary contacts 208 and 209, respectively. Suitablebiasing means are ;provided whereby the said movable contact blades arereturned to the position shown in Figure 2 upon the'winding 202a beingdeenergized. Engagement of contact arm 206 with station-ary contact 20-8will result/in energization of the -hea-t-' ing mean throughthevfollowing circuit: from line 'wire 2I0'through Wire 2I I, contact arm2.06, contact 208, wire 2I2, heating means 200 and wire 2I3'back to theother'line wire 52M.

The cooling relay 203 includes a relay winding :203a which whenenergized movesrelayarms '2 I5,

2I6, 2I1, 2H8, and 2H! into engagement with stationary contacts 220,22I, 222, 22.3, 224,.and 225.

. Suitable biasing means are provided whereby the saidrelay arms arereturned to the position shown in Figure 2xupon the winding 203a beingdeenergized. Engagement of the contact arm :2l9 with the stationarycontact 225 will result in energization of the cooling means 20I throughthe following circuit: from line wire 2I0 through wire 226, contact arm'2I9, contact 225, wire 221, cooling means 20I and wire 228 back to theother line wire 2.

The heating and cooling relays 202 and 203 ,receive electricalenergyfrom a transformer generally indicated by the reference character230 Such setting will in no ends to an ear glosses 11 which comprises ahigh voltage primary 23l and a low voltage secondary 232. The relays 202and 203 are under the control of a thermostatic device generallyindicated by the reference character 235.

The controller 235 comprises a base 235 which may be of insulatingmaterial and upon which a pivot post 231 is secured. Freely pivoted uponthe post 231 by means of a bracket 238 is a bimetallic strip thermostat240. At the lower right-hand end of the bimetal strip 240 is carried apair of movable heating control contacts 24! and 242. The contact 242 ismounted upon a resilient strip 243 so that it may be pressed back afterengaging its stationary contact. The contact 242 cooperates with astationary contact 244 which is carried upon a conducting bracket 245which may extend to the rear of the base 236. The contact 24! cooperateswith a stationary contact 245 which is secured to a conducting bracket241 which likewise may extend to the rear of the base 236.

At the lower left-hand end of the bimetallic strip 245 are a pair ofcooling control contacts 250 and 25!. resilient strip 252 so that it maybe pressed back when engaging its stationary contact. The movablecontact 25! cooperates with a stationary contact 253 carried upon aconducting bracket 254 which is secured to a movable insulating plate255. The contact 250 cooperates with a stationary-contact 256 which issecured to a conducting bracket 251 which likewise may be mounted uponthe plate 255.

.An adjustable stop 258 is mounted upon the movable plate 255 and isadapted to cooperate with the lower left-hand end of the bimetal andserve as a bearing against which the bimetal may abut and rotate aboutits pivot 231' so as to operate the heating contacts upon a decrease intemperature as indicated by the legends on the drawing. The stop 258 ismade adjustable to vary the effective spacing of the contacts, and.--hence the changeover temperature differential. A fixed stop 255cooperates with the lower righthand end of the bimetallic strip 240 andthe strip is adapted to bear thereupon and rotate around its pivot 231to cause the movable cooling control contacts 250 and 2 51 to engage thestationary contacts 256 and 253.

' 'An adjustment arm 250 is also pivoted upon the post 231 and is biasedfor clockwise rotation by a spring 25! which is secured at one of its232 on the base 236 and secured at its other end to the upper extendingportion ofthe arm 260. l The upper part of the arm 260 cooperates withan adjustment earn 263 which may be rotated by an adjustment dial 264having indicia 255 thereupon which cooperate with a pointer 266 toindicate the setting of the device.

A light spring 210 is secured at one of its ends to the bimetallic strip240 and at its other end to the adjustment arm 250. The spring 210 urgesthe bimetallic member 240 as a whole in a clockwise direction to theleft so that one or the other of the ends will engage either of thestops 258 or 259. A pair of heaters 21! and 212 are arranged inproximity to the bimetallic strip 240. I These heaters are selected togive a predetermined degree of heat to the bimetal under certain opereating conditions to be described more fully hereinafter.

Operation on heating When the bimetallic strip 240 is subjected tea Thecontact 25! is carried upon a decreasing temperature and the device as awhole 75 is operating upon heating, the lower left-hand end of thebimetallic strip 240 will be in engagement with the adjustable stop 258.The lower right-hand end of the bimetal 240 will move toward thestationary contacts 244 and 246. The first contacts to engage will bethe movable contact 242 and the stationary contact 244. At this timehowever, no circuit for the relay coil 202a will be established becauseof the fact that the contact 200 will not be engaged by the relay arm201. However, when the movable contact 24I engages its stationarycontact 240, a circuit to the relay winding 202a may be traced asfollows: from the secondary 232 of the transformer through wire 215,wire 21$, bracket 245, contact 244, contact 242, contact strip 243,contact 24l, contact 246, bracket 241, wire 211, relay coil 202a, wire218, and wire 219 back to the other side of the transformer secondary.This circuit will cause the relay to pull in and the relay arms toengage stationary contacts. Engagement of the relay arm 205 with thecontact 208 will cause energization of the heating means through thecircuit hereinbefore traced.

When the heating means has operated for a suitable length of time, aslight rise in space temperature will occur. Upon a rise in spacetemperature the contact 241 will separate from the stationary contact246. However, at this time the contacts 242 and 244 will not beseparated inasmuch as they engage slightly before engagement of contacts2 and 246. Hence, a circuit for maintaining the relay energized untilthe contacts 242 and 244 separate may be traced as follows: from thesecondary 232 of the transformer through wires 215, 216, contact bracket245, contacts 244 and 242, contact strip 243, bimetallic strip 240, wire280, heater 212, wires 28I and 282, contact 229, relay arm 201, wire283, relay winding 202a, wires 218 and 219 back to the other side of thetransformer secondary 232. It is noted that in this circuit the heater212 will be energized and therefore will give heat to the bimetallicstrip 245 to speed up its operation in separating contacts 242 and 244..Hence, it is seen that I have provided a delayed heat anticipationaction in this circuit. During the period of time that the contacts MIand 246 for pulling the relay in remain in engagement, the heater 212will be shunted out and therefore this heater will not affect theoperation of the bimetal until after these contacts are separated.

Operation on cooling In order to give a delayed cooling anticipation Ihave provided means to supply heat to the bimetal at all times exceptduring a certain portion of operation of the cooling means. A circuitfor heater 21! which is on at all times except for this period of timemay be traced as follows: from the transformer secondary 232 throughconductor 215, conductor 285, variable resistance 285, conductor 281,out contact 224 of the relay 203, contact arm 2l8, conductor 288, theheater 21!, conductor 289, and conductors 290 and 219 back to the otherside of the transformer secondary 232. From this circuit it is seen thatwhen the cooling means are not in operation that a given degree of heat,for example for 3, may be supplied to the bimetal at all times. It willalso be noted that this heater is normally in operation, even when thethermostat is operating the heating means.

Upon an increase in space temperature, the lower right-hand leg of thebimetallic strip 240 '13 will move into engagement with the stop 259.Thereafter the lower left-handend of the bimetallic strip 240 will moveaway from its stop 258 and into engagement with the stationary contacts.The'first contacts to make as this temperature rise takes place are themovable contact 25! and the-stationary contact 253. However, at thistime no effect will be had upon the relay.

Upon a further increase inyspace temperature the movable contact 259will engage the stationary contact 258. When these last to engagecontacts make, an energizing circuit for the relay winding 203a may betraced as follows: from the secondary 232 of the transformer throughconductors 215, 216, 29!, bracket 254, contacts 253 and 25!, contactcarrier-arm'252, contacts 258 and 256, contact bracket 251, wire'232,relay coil 293a, wire 293, relay arm 2 l1, relay out contact 222, wire294, and wires 290-and 219 back to the other side of the transformersecondary.

Once the'cooling relay 293 has been energized,

"a new relay circuit including the heater 21! may be traced as follows:from transformer secondary 232, wires 215 216 and 29!, contact bracket254,

contacts 253, 25!, contact carrier 252, contacts 259 and 253, contactbracket 251, wire 292, relay winding 293a, wire 293', relay arm 2! 5,contact 22!, wire 295, contact 223, relay arm 2E3, Wire 288, heater 21!,wire 289, and wires 29!: and 219 back to the other side of thetransformer secondary 232. The original circuit for heater 21! wasbroken at 2*!8-224, as was the original circuit for relay coil 203m at2!1222, upon the initial energization of relay coil 203a. However, therelay arm 2!8 upon the initial energization of the winding 203a isadapted to engage contact 223 prior to the opening of the contact 222 byarm 2 I 1. Likewise the contact 222 is adapted to remain closed untilthe stationary contact 22! is engaged by the arm 2l6.

Hence, it is seen that the heater 21!, which is energized when theheating relay- 233 is deenergized, is also energized when the relay isenergized so long as the movable contact 253 remains in engagement withits stationary contact 253.

When contacts 253 and 253 separate indicating that there has been somecooling. in the space which results in a slight movement of contact 25%]away from contact 252, it is desirable then to remove the heat from thebimetal to give delayed cooling anticipation. Hence, I have provided afurther holding circuit having a high resistance so that the effect ofthe heaters 21! and 212 will be very slight. This circuit may be tracedas follows: from the transformer secoindary 232 through wires 215, 216,and 29!, contact bracket 254, contact 253, and 25!, contact arm 252,bimetal strip 259, the mountingbracket 238, wire 28!], heater 212, wire28 I, wire 2 96, large resistance 291, wire 299, contact 220, relay arm2l5, wire 299, relay winding 293a, wire 293, contact arm 2H5, contact22!, wire 295, contact 223, relay arm 2N3, wire 288, the heater 21!,wires 2B9, 29!], and 219 back to the other side of the transformersecondary 232. It is seen upontracing the above circuit that theresistance of both heaters 21! and 212 adjacent to the bimetal 249 arein series with a considerably larger resistance 291. By such anarrangement, the impedance on the circuit is such that the effect of theheaters 21! and 212 upon the bimetal is negligible, for example in theorder of one-fourth to one-half of one degree. Hence, the bimetallicmember 229 will sense this effective cooling which will result inaccelerated movement of the movable contact 25! away from the-stationarycontact 253.

By -such structure it is seen that I have provideda novel coolinganticipation type of structure.

'It will be noted upon tracing the circuit for heating the bimetal whenthe cooling-relay is deenergized, that this circuit includes thevariable resistance .286. The resistance 285 is so constructed that itsimpedance in thiscircuit will be substantially the same as the impedanceof relay winding 29311. The reason for this is that by-such structurethe heating to the bimetal 230 when the relay is off will besubstantially the same as when the contacts 259 and 256 engage becausethe impedance in the circuit will be substantially the same.

The modification shown in Fig. '3

The device disclosed in Figure 3 will now bedescribed. In Figure 3, Ihave illustrated a heating means 330 and a cooling means 32!. Theheating means is controlled by a snap action switch generally indicatedby the reference character 392 and the cooling means is control-led by asnap action switch generally indicated by the reference 393. When thecontacts in the switch 332 are closed, a circuit is completed foroperating a heating means from line wires 33:3 and 305. When thecontacts of the snap switch 333 are closed a circuit for the coolingmeans is closed from the line wires 396 and 301.

A control device for operating the snap switches 332 and 333 isgenerally indicated by the reference character 3). The'control device3!:6 comprises a base 311 upon which a bimetallic strip 312 is mountedupon a post 3E3 by means'of a bracket 3M. An adjustment means, which issimilar in all respects to the adjustment means described in connectionwith Figure 2, is generally indicated at 3l5. An adjustment arm 3H3carries a plate 311 which mounts a stop 3L8 for the lower left-hand endof the bimetal and the snap switch .303. A spring 329 biases thebimetallic strip 312 towards the stop m as well as toward a stop 3!9.The stop 3!9 is adapted to cooperate with the bimetallic strip 3 2 andserves as an abutment whereupon the strip may bear to actuate thecooling snap switch 303. The adjustable stop 3!8 may be rotated to varythe differential of change-over of the switch and cooperates with thebimetal in operation of the heating switch 302.

Inasmuchas the snap switches 3.32 and 303 are identical, only one ofthem will be described. When operating the cooling means, the bimetal 3!2 will be heated and the ends will move toward each other. The lowerright-hand end of the bimetal will bear upon the abutment M9 and thelower left-hand end will force a plunger 33%] inwardly. This plunger33!] builds up a force in a spring 33! which bears at its innermost endupon a movable cup 332, the cu in turn bears against a switch arm 333,which is pivoted at its lower end at 334 and at its upper end carries amovable contact 335. The movable contact is adapted to cooperate with astationary contact 336 to make and break the circuit to the coolingmeans 39!. A spring 331 biases the switch blade 333 in acounter-clockwise direction with a force which is predetermined by theangle of force application between it and the switch arm 333. Hence,when sufiicient force has been built up in the spring 332 by a movementof the plunger 33!) toward the right, the switch arm .333 will begin tomove in .a clockwise direction. Thesprings limit control or the like.

332 and 331 are so selected that the resistance to movement of theswitch arm 333 by the spring 331 falls off at a rate more rapid than thedecrease in force due to the action of spring 332. Hence, what is knownas a spring rate compensation or over compensation snap action isobtained. It will be understood that other snap action structure couldalso be utilized, for example magnets or overcenter snap switches.

After the contacts 335 and 335 have been made for a sufficient length oftime the air affecting the thermostat 3l2 will become cool and cause thelower ends of the bimetallic strip 312 to separate. This separation willrelieve the force in the spring 332 and the force of the spring 33'!acting upon the contact arm 333 will cause the arm to snap away andseparate th contact 335 from the contact 336, thus shutting off thecooling means.

The heating means switch 302 operates in an identical manner to theoperation of the cooling means switch except for the fact that uponcooling the switch 302 is made to energize the heating means and uponheating the switch is opened so that the heating means will bedeenergized.

From th foregoing, it will be seen that I have disclosed severalmodifications of my invention for obtaining both heating and coolingcontrol having an automatic change over and control mechanism forpreventing overshooting of the delayed anticipation type. My presentinvention embodies features which may be found applicable in othercontrol applications, for example It will be understood, however, whileonly several embodiments of the invention have been described andillustrated in the drawings, that the invention is not limited thereto,but is capable of a variety of mechanical forms and that changes may bemade in the form, details of construction and arrangement of the partswithout departing from the spirit of the invention. Reference shouldtherefore be had to the ppended claims for definition of the limits ofthe present invention.

I claim:

1. A heating and cooling system comprising, in combination, heatingmeans, cooling means, first control means fOr said heating means, secondcontrol means for said cooling means, a movable condition responsivemeans, and a plurality of abutment means for said condition responsivemeans, said condition responsive means acting upon a first and second ofsaid abutment means to operate said first control means, and upon saidsec-0nd and a third of said abutment means to operate said secondcontrol means.

2. In a heating and cooling system, in combination, heating means,cooling means, a circuit therefor, and control means in said circuitcomprising a bimetal strip pivoted at a point between its ends, firstand second abutment means adjacent said ends, and a pair of switchesadjacent said ends, one of said switches being actuated by said stripupon cooling to operate said heating means and the other of saidswitches being actuated thereby upon heating to operate said coolingmeans, said strip acting upon the first of said abutment means androtating about its pivot point to actuate one of said switches, andacting upon the second of said abutment means and rotating about itspivot point to actuate the other switch.

3. In a heating and cooling system, in combination, heating means,cooling means, a circuit therefor, and control means in said circuitcomprising a bimetal strip pivoted at a point between its ends, firstand second abutment means adjacent said ends, and a pair of snap actionswitches adjacent said ends, one of said switches being actuated by saidstrip upon cooling to operate said heating means and the other of saidswitches being actuated thereby upon heating to operate said coolingmeans, said strip acting upon the first of said abutment means androtating about its pivot point to actuate one of said switches, andacting upon the second of said abutment means and rotating about itspivot point to actuate the other switch.

4. In a heating and cooling system, in combination, heating means,cooling means, a circuit therefor, and control means in said circuitcomprising a bimetal strip pivoted at a point between its ends, a pairof switches adjacent said ends, one of said switches controlling saidheating means and the other of said switches controlling said coo-lingmeans, and means for causing automatic changeover from control by one tothe other of said switches consisting of abutment means, said abutmentmeans being adjustable for varying the changeover temperaturedifierential.

5. A heating and cooling system of the class described, comprising, incombination, electrical- 1y operated heating means, electricallyoperated cooling means, thermostatic means, switching means operated bythe thermostatic means, local electrical heatin means for saidthermostatic means, means including electrical connections between saidswitching means, electrically operated heating means and said localheating means operable to energize said electrically operated heatingmeans when the temperature falls to a predetermined value, toadditionally energize said local heating means while maintaining saidelectrically operated heating means energized upon a first rise intemperature from said predetermined value, and to deenergize both saidlocal heating means and said electrically operated heating means upon astill further rise in temperature, second switching means operated bysaid thermostatic means upon further temperature rise, means includingelectrical connections between said second switching means and saidlocal heating means to energize the local heating means upon suchfurther rise in temperature, third switching means operated by saidthermostatic means upon still further temperature rise, and meansincluding electrical connections between said third switching means,electrically operated cooling means and local heating means to maintainsaid local heating means energized and to energize said electricallyoperated cooling means upon such further temperature rise so as toreduce such temperature, to energize said local heating means to alesser degree while maintaining said electrically operated cooling meansenergized upon a first temperature fall, and to deenergize saidelectrically operated cooling means and reenergize said local heatingmeans to the griiginal extent upon still further temperature 6. In acombined heating and cooling system, in combination, a pair oftemperature changing means comprising heating means and cooling means,temperature responsive means in control of said heating means andcooling means to operate said heating means at a predetermined lowtemperature and to operate said cooling means at a predetermined hightemperature, means for adjusting said temperature responsive means tochange the temperature at which one of-said tem-" per'ature changingmeans is operated, means to prevent the operationof the other of saidtemper'ature changing means, and a, single means for operating both saidadjusting means and said preventing means. V

7. In a combined heating and cooling system, in combination, a pai oftemperature changing means comprising heating means, and cooling means,temperature responsive means in control of said heating means and coolinmeans to operate said heating means at a predetermined low temperatureand to operate said cooling means at a predetermined high temperature,means for adjusting said temperature responsive means to change thetemperature at which one of said temperature changing means is operated,means to prevent the operation of the other of said temperature changingmeans, and a single manually settable timing means in control of saidadjusting means and said preventing means.

8. In combination, a pair of temperature changers comprising a heatingmeans and a cooling means, temperature responsive switching means incontrol of said heating means and cooling means, means to adjust thetemperature at which one of said temperature changers is operated bysaid temperature responsive switching means, and switching meansoperated by said adjusting means to prevent operation of the other ofsaid temperature changers b said tempera:

ture responsive means.

9. In combination, 'a pair of temperature changers comprising a heatingmeans and a cooling means, temperature responsive switching means incontrol of said heating means and. cooling means, means to adjust thetemperature at which one of said temperature changers is operated bysaid temperature responsive switching means, switching means operated bysaid adjusting means to prevent operation of the other of saidtemperature changers by said temperature responsive means, and manuallysettable timing means in control of said adjusting means.

10. In a cooling system, electrical means to provide a cooling actionwhen energized, a temperature responsive element, switching means havingthree switch closing positions operated thereby, said positionscomprising a cold position, an intermediate position and a hot position,local electrical heating means for said temperature responsive element,and means including circuit connections between said electrical means,switching means and local electrical heat ing means arranged to energizesaid local electrical heating means a predetermined amount when theswitching means is in said cold posi- 18 ing 'of the temperature, and tothereupon stop saidele'ctrically operated cooling means and reenergizesaid local heating means said predetermined amount. 11. In a cooling"system; electri'cal'means to provide a cooling action when energized, atemperature responsive element, switching means having three" switchclosing positions operated thereby, said, positions comprising a coldposition','an intermediate position and a hot position, a localelectrical heating means for said temperature responsive element, relaymeans including switches operated thereby, and circuit connectionsbetween said electrical means, switching means, local electrical heatingmeans and relay means arranged to energize said local electrical'heatingmeans a predetermined amount when the switching means is in said coldposition, said circuit connections, switching means and relay operatedswitches being arranged to maintain said energization of said localheating means substantially constant as said switching means are movedthrough said intermediate position to said hot position by risingtemperature and'to energize said electrical means to cause' 1 switchingmeans out of said hot position due to tion, said means including circuitconnections and switching means being arranged to maintain saidenergization of said local heating means substantially constant as saidswitching means are operated through said intermediate position to saidhot position by rising temperature and to energize said electrical meansto cause cooling when the switching means moves to said hot position,said means including circuit connections coacting with said switchingmeans to continue the operation of said electrical means causing coolingand to diminish the energization of said local heating means upon movingof the switching means out of said hot position due to loweredtemperature, the energization of saidlocal heating means remainingsubstantially diminished until movement of said switching means throughsaid intermediate position upon lowerlowered temperature, theenergization of said local heating means remaining substantiallydiminished until movement of said switching means through saidintermediate position upon lowering of the temperature, and to thereuponstop said electrically operated cooling'means and reenergize saidlocalheating means said predetermined amount.

12. In a cooling system for a medium, in combination, an electricallycontrolled cooling means; means responsive to the medium temperature; a

plurality of switch means arranged to be sequentially operated by saidtemperature responsive means; local electric heating means for saidtemperature responsivemeans; relay means for controlling said coolingmeans and having a winding; a first resistor having substantially thesame electrical impedance as said winding; a

second resistor; and electrical circuits controlled by said sequentiallyoperated switch means so that, at one sequential position due to arelatively low medium temperature, the local heater is energized inseries with said first resistor, at another sequential position due to ahigher medium temperature the first resistor is deenergized and thewinding is energized in series with the heater, energizing the relaywinding causing operation of the cooling means, and at a furthersequential position corresponding to said one position and caused by theoperation of said cooling means loweringthe medium temperature, thesecond resistor is energized in series with said winding and saidheater.

13. In a system for controlling the temperature of a medium, incombination, an electrically controlled temperature changing means,means responsive to the medium temperature, a plurality ofswitch meanssequentially operable by said temperature responsive means, localelectric heating means for said temperature responsive means, relaymeans for controlling said temperature changing means and having awinding, means including an electric circuit controlled 1 9 byvsaid;switch. means when. in. a. sequential positiondue, to. a predeterminedtemperature for energizing; saidheater byan electric current. ofpredetermined value, means including a different electric circuitcontrolled by saidv switch means when at. a, different sequentialposition due to a temperature other than said predetermined temperaturefor energizing said winding in series with said heater and maintainingthe current flow through said local heater at said predeter- 10 20mined. value; and, means. including another electric circuit controlledby said switch means when at a third sequential position, due to, atemperature caused by operation of said temperature changing means forenergizing said winding and for changing the current flow insaid localheater in a manner to anticipate a further change in temperature due tooperation of said temperature changing means.

GI'FFORD I. HOLMES.

